At Navy Pier, Eating Like Bird Means Nibbling Roof

In 1945, the powerful Mark II computing machine at Harvard University was chugging along, laboriously crunching numbers, when it sputtered to a stop.

Technicians scoured the massive machine for the problem and found a most unlikely cause: a four-inch moth wedged inside a switch.

At that moment, the computer term "bug" was born, freezing that moth in a kind of linguistic amber. It also forever preserved a complex idea: that nature's tendrils will work their way into even the grandest of designs.

Proof arose this week at Navy Pier, where gulls have been pecking at a small section of roof on the new exhibition hall.

For some reason, the birds attacked a translucent sealant used to bridge joints where vaulted sections of the roof come together.

The damaged area covers about 1,400 feet. Officials said most of the 13 miles of caulking used on the pier's controversial roof system is made of a different material and was unscathed.

The problem came to light on Sunday afternoon, when rain water began pouring onto a trade show. `

"At one point in time it was quite frightening because a lot of water came in through many areas," said David Lefever, executive director of the National Association of Fleet Administrators, which was holding its annual convention at the pier.

But somewhere, some minute force of nature, as subtle as the twitch of a hungry mouse's nose, is sure to wreak havoc again.

Zebra mussels will clog water filtration plants. Squirrels will chew power lines. Kudzu will overtake a fence line.

"Most organisms are not passive victims of their environment, they tend to react to hazards and opportunities," said Joel Brown, a biology professor at the University of Illinois at Chicago. "As far as you change the environment, it will be used by the critters."

Last year, the launch of the space shuttle Discovery was delayed for months after two woodpeckers attacked the fuel tank. Seeking insects in the insulation around the tank, the birds bored 135 holes, some as large as compact discs.

In 1991, a bird tried to make its home in an attractive building in Iowa City. Unfortunately, the building was a toothpaste plant for Procter & Gamble and the bird wound up in a 180,000-pound vat of Gleem, ruining the batch.

Last year, an Air France Concorde was flying into Kennedy International Airport as a flock of Canada geese was flying out. The birds were sucked into the engines, causing two of them to catch fire.

The plane landed safely, but airport officials shook their heads. "We have a running battle out there with the birds," one said.

In Chicago, raccoons and opossums destroy 4,000 to 6,000 garbage containers supplied by the Department of Streets and Sanitation, according to Terry Levin.

In the South, a water weed, hydrilla, has become such a pernicious problem that some power plants have been forced to run for a few hours, then shut down to clean out the intake valves.

"As humans go about changing our environment, we are not destroying all of nature," Brown said. "Nature is responding and moving around us."

Animals, mostly squirrels, cause about 2,800 power outages a year in the Chicago area, according to Joe King, a spokesman for Commonwealth Edison. They chew on the insulation around the transformers and eventually complete the circuit.

"The industry has spent thousands, even millions of dollars trying to find a solution to this," King said. "If you have ever tried to keep a squirrel off your bird feeder, you know how hard it can be to beat these guys."

At Navy Pier, engineers will now try to beat the gulls. As a short-term fix, workers put out buckets and plastic sheets and applied temporary silicone patches to the roof.

The roof on the remodeled Navy Pier has been controversial from the start, and this week's leaks aren't the first at the pier.

Before last year's grand opening, the Metropolitan Pier and Exposition Authority, which runs the pier and McCormick Place, had rigged buckets and hoses on the exhibition hall's ceiling. Authority officials said those problems were caused by improper drains.

Birds nibbled at the caulking before it had dried, causing minor leaking last spring during the first event held at Festival Hall, Art Chicago 1995.

Jon Clay, the pier's general manager, said the damaged sealant will be covered with metal sheeting in the next week to deter the birds. He said repair costs will be borne by the general contractor, Schal Bovis Inc.; Schal officials couldn't be reached for comment.

Anita Cramm, curator of birds at the Lincoln Park Zoo, said gulls probably were attracted by the appearance of the sealant, though she wasn't sure why they might find it appealing.

"Birds are very visual," she said. "They have to be visually attracted to spots in the roof or the roof in general. It could be something shiny."

Gulls have strong, pointed beaks and are adept at finding types of food that other birds might overlook, Cramm said. She added, however, that sealant probably has little nutritional value.

Clay said the birds may have been trying to eat insects embedded in the sealant.

A spokesman for Dow Corning Corp. in Midland, Mich., which makes the translucent sealant and the other caulking used on the pier's roof, said the company isn't to blame for Navy Pier's roof troubles.

"Bird-pecking on this sealant is rare and bird-pecking occurs on other materials besides sealant," he said. "The Navy Pier location is unique because it has been a major bird habitat for 20 years."